In 'Machine Gun Preacher,' Gerard Butler plays a former junkie biker who finds God, then becomes a savior to children in war-torn Sudan and Uganda. Sounds far-feteched, but it's all based on the true story of Sam Childers, a tough character who cleaned up, started his own church and then decided to go to the Sudan and save as many of its orphans as he could. The atrocities depicted in 'Machine Gun Preacher' make it a hard sell, but Butler's been crossing the country in support of the film, which he also co-produced. He talked to Moviefone about playing a gun-toting preacher with a messianic complex and how the movie changed his life.

What kind of research did you do for this movie?
For a year after I first read the script, we did a lot of sessions, myself, [director] Marc Forster and Jason Keller the writer. We'd lock ourselves in a room for 9 to 12 hours and just work through the script. It was always great, but it needed a lot of finessing and cutting down.

How did you get a handle on playing Sam?
I had to break down the components of Sam: There was Sam the biker, so I got all these books on bikers and watched all these biker movies and documentaries. I went out a couple of times -- I don't have a Harley, but I went out with a biker gang.

Then there was the preaching. I went crazy on Youtube watching preachers and getting their style. And I actually went to Sam's church in Pennsylvania and I got extra footage of him preaching.

Then there was obviously, the Sudan, that situation. There's just a huge amount of information and you work from that. And more than anything, just time spent with Sam and his book of course. It's a bit dry, really (mocking tone): "I watched a lot of documentaries." The rest of it is a journey in your own mind. That's where most of the work goes on, getting the swagger and starting to think like him and getting to the same emotional space.

He's a controversial character. Did you have any qualms about playing a man who shoots child soldiers?
I did have qualms, but not so much about that, because that's all part of the story. The qualms were more, 'Could I pull it off?' It felt like a big role to take on. I loved the emotional parts. They hit me like a ton of bricks. I felt if that's what I experienced, how amazing to make other people feel even one tenth of that. But we always had to be careful how much we went into the violence and how it was told, but the violence per se didn't put me off playing the role.

How hard was it to film scenes where you're witnessing these horrible atrocities against children?
To me, strangely enough, that was the most rewarding about it. The more you put into it emotionally, the more reward you get out of it. I felt we had to earn it. But without a doubt, I spent a lot of time going into dark holes. Those documentaries I would watch and the reading was all about heartbreaking, disastrous, awful human situations: people being beaten to death and kids mutilated, mass graves, mothers with babies and knapsacks on their back, all cut down. I went into the darkest parts of my own life to get yourself to that space that you have to be in, when you sit in front of 14 kids burned alive or holding a kid blown in half in your arms. They were tough and I would get very emotional even at times I wasn't supposed to, it would just come up and kind of grab you. When I started doing this press junket, that happened in talking about the movie, having spent so much time around that story. These people, these children, you imagine being one of them and it just really starts to become part of your DNA.

Where did you film the movie?
The worst parts of Detroit. A lot of the story takes place in trailer homes and crack houses. And then we went to South Africa, to the countryside, outside Johannesburg. It's very sparse out there but beautiful. It was a great setting for Sudan and you just get lost in how epic these landscapes were.

Did you meet any refugees from the Sudan?
We actually had a couple on the movie and we had a dialect coach from there as well. Her sister had her lips cut off by the LREA [cruel rebels, known as the Lord's Resistance Army, an incident that happens to one woman in the movie]. They literally left her for a few minutes and when they came back, she'd lost her lips. And one of her security guards had fought for the Sudanese People's Liberation Army and he had a lot of incredible stories too. They all have these stories, like children who've killed 60 people. This is why I love this movie, though. You can say that and it's just a number, but when you watch this movie it all becomes real.

So what did you take away from this movie? How has it changed your life?
I'm actually really proud and honored that I took this on. We were taking a risk by making a movie where a white man goes to Africa and saves black children. You're putting yourself up for a lot of criticism. But I do believe everyone made it for the right reasons and it is a true story and it is an inspiring story. I've sat through screenings all over the country and it's been incredible, how much it moves people. It reaffirms my belief in humanity. The movie and this story in some ways damaged that, to see humans do this to each other. It does leave you really depressed and despairing. And then you make this movie about somebody who stood against that and you see how people react and how much compassion and humanity it brings up in them and that has been a really joyous experience for me. If you go to a cinema, pretty much everyone has the same reaction. They get past the cynicism that certain people would have, like the reviewers [the movie has a 22% critics' store on Rotten Tomatoes], and they feel very strongly and that has made all of this so worth it for me.

Do you think you might want to do something lighter next time?
There's only so many 'Machine Gun Preachers' in me. But I have to say, there's actually a lot of light moments in it. Sam is a funny guy, so even in a darker movie, you get the lighter moments in. But I want do to some lighter movies, I want to do action, thrillers, maybe space out a another musical, I'm doing another animated movie. I want to keep challenging myself and keep doing new stuff. I have a Shakespeare coming out ['Coriolanus' with Ralph Fiennes]. I don't want to ever, I hope, make it too easy for myself.

You play a soldier in 'Coriolanus.' Why are you so drawn to -- or so good at -- these military roles?
I don't know. I didn't even thinking of it like that. I never saw Sam as military in my head, I see him as a preacher who just carries a gun. I didn't even realized 'till you said it. I guess I'm a guy, I'm a guy's guy. Those questions are hard to answer because it's like saying, "Why did you get cast in the movie?" And there's no way to answer it without singing your own praises: "Well, because I'm a tough sonofabitch and I'm a badass like nobody else." I'm joking, of course. And it goes into print and people are like, "Oh yeah, great, listen to him."

'Machine Gun Preacher' is currently in theaters.' 'Coriolanus' is set for a January 2012 release. We'll have more of Butler's interview about working with Ralph Fiennes in 'Coriolanus' soon.